Different rechargeable batteries such as lead-acid batteries, nickel cadmium (NiCd) batteries, nickel metal hydride (NiMH) batteries, and lithium ion (Li-ion) batteries have been developed and widely used. Among the various types of rechargeable batteries, lithium ion batteries are known to be commonly applied to consumer electronic products such as portable electronic devices due to their relatively compact size, light weight and high energy density.
Nevertheless, lithium ion batteries are also known to present safety risks and may even be dangerous such as during a thermal runaway event, which may result in flaming or even an explosion of the battery. For example, thermal runaway in a faulty rechargeable battery may be caused by an internal short circuit of the battery due to an external impact or crash of the battery. The internal short circuit can cause heat generation which may shrink the battery separator, and can result in a more severe short circuit. Thermal runaway may also be caused by overcharging of a rechargeable battery, which also generates excess heat. Traditionally, thermal runaway of the rechargeable battery can be prevented, minimized or reduced by, for example, avoiding generation of heat due to a short circuit and/or providing heat resistant layers at the separator of the rechargeable battery. Poor air permeability of the heat resistant layer may further affect performance of the battery.